The nitrogen passivation of GaSb by etching method layer by layer is conducted based on the plasma enhanced atomic layer deposition (PEALD) system, and the influence of etching cycle in the passivation process on the passivation effect of GaSb is discussed. The study results show that, the passivation effect is the best when the etching cycle number is 200. When the etching cycle number is smaller than 100, the passivation effect is the weakest. When the etching cycle is relatively higher (300-400), the larger the etching cycle number is, the weaker the passivation effect is.